Stent coverage and neo-intimal growth can be evaluated in-detail by intracoronary optical coherence tomography (OCT), which is a catheter-based imaging technique. It is performed as part of the PCI procedure. OCT is the optical analogue of intravascular ultrasound (IVUS), except that it can provide much higher resolution of coronary cross sectional images than IVUS. The LightLab C7XR OCT system (Frequency Domain OCT) used in this Hospital has obtained full CE Mark, approved by the US FDA, and approved for clinical use in Hong Kong. It has been shown to be safe in clinical settings and has been used in over 300 patients without complication at Queen Mary Hospital.